Watch out, line cutters. American Airlines is rolling out new technology across the country to crack down on travelers trying to get on the airplane before their boarding group is called.Customers who try to scan a boarding pass before their group is called will hear a two-note sound and be turned away, the airline said.American Airlines has nine boarding groups, ranging from first-class customers and top-tier frequent flyers to travelers who purchased basic economy fares, or the least-expensive tickets. Ai ...